Telephone-exchange system.



J. L. WRIGHT.

TELEPHONE EXCHANGE SYSTEM APPLICATION FILED DEC. 18. {9!4- v Patented J11ly17, 1917.

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IVIIQVESSES MWR My mi i J. L. WRIGHT.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED DEC. 18. 1914.

Patented July17, 1917.

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WITNESSES;

J. L. WRIGHT.

TELEPHONE EXCHANGE SYSTEM.

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I/l/l/E/VTOR J. L. WRIGHT.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED DEC. 18, 1914.

Patented July 17, 19W.

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J. L. WRIGHT.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED DEC.18, 1914.

Patented July 1, 1917.

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WITNESSES: jiigE/VTOR J. L. WRIGHT.

TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED DEC. 18. I914.

Patented. July 17, 1917.

II SHEETSSHEET 6.

QPR T EL S T I VITNESSES J. L. WRIGHT.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED DEC. 18. I914.

Patented July 17, 1917.

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APPLICATION FILED DEC-1811914.

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WITNESSES M All J. L. WRIGHT.

TELEPEIONE EXCHANGE SYSTEM. APPLICATION FILED DEC-18,1914.

Patented July 17', 1917.

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J. L. WRIGHT. TELEPHONE EXCHANGE SYSTEM.

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.I. L. WRIGHT.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED DEC. I8. I9I4.

Patented July 17, 1917.

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I e N n K0 1 WITNESSES I l/VVf/I/TUI? M M do! ZLA/ erators position.

JOSEPH L. WRIGHT, OF CLEVELAND, OHIO, ASSIGNOR, BY MESNE ASSIGNMENTS, TO

WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORATION OF YORK. I

TELEPHONE-EXCHANGE SYSTEM.

I Specification of Letters Patent. Patented July 1LT, T9111)?Application filed December 18, 1914. Serial No. 377,872.

To all whom it may concern:

Be it known that ll, JOSEPH L. WRIGHT, citizen of the United States,residing at Cleveland, in the county of Guyahoga and State of Ohio, haveinvented-certain new and useful Improvements in Telephone-ExchangeSystems, of which the following is a specification.

My invention relates to telephone exchange systems and especially to thetype known as semi-automatic. In systems of this class automaticswitches are utilized for efi'ectin connections between subscriberslines. ertain of these switches are purely automatic in their action andperform selections without such'selections beingpredetermined either bythe subscriber or the operator. Other switches which are controlled bythe operator perform their selections in a predetermined order.

'Heretofore corresponding switches which were driven in a predeterminedmanner were provided with test contacts and wipers for selecting trunksor terminals of other switches. With myinvention the calling lines areautomatically selected by means of primary switches and these switchesin turn are automatically connected to an idle op- The switches whichare under control of the operator perform their selections in apredetermined manner with out the necessity of testing. Certain switchescontrolled by the operator are driven directly to contacts of calledlines, while other switches are driven in a predetermined man'- ner tocontacts associated with primary trunksto which calling lines areconnected.

The calling lines besides being automatically connected to an operatorsposition over what may be termed order trunks also cause to be indicatedatsuch position the number corresponding to the number of the primarytrun s. I The operator ascertains the number of the wanted line from thecalling subscriber over these order trunks. In order to extend theconnection, the operator is provided with a suitable key-board andsending device. The number of the primary trunk as indicated isregistered upon the key-board as well as the number of the wanted line.By means of the impulse device a pair of coupled or mated switches areoperated, one of which selects contacts corautomatically connecting herkey-board or sending device with an idle service trunk. After an idleservice trunk is selected the order trunk is automatically disconnectedfrom the operators position and placed in readiness for receiving otherincoming calls. The key-board and order trunk are not permanentlyconnected and under ordinary conditions a single order trunk and singlekey board will be ample for one operator. While the connection is beingestablished. between the primary trunk and the called'or'wanted line theorder trunk is in position to receive another call While the operator isascertaining the number of the wanted line the key-board is released andin condition to receive the registration of the second call.

Means are provided for maintaining the order wire trunk in associationwith the connection after it is extended to the wanted line in orderthat the operator may supervise the connection.

Other special features are provided whereby the ringing which isautomatic is discontinued in case the called subscriber does not answerwithin a reasonable time. At this period the connecting switches areautomatically released and a dont answer signal connected to the callingline.

Special releasing features are provided in connection with the connectorswitches whereby it is unnecessary for a calling subscriber to exercisecontrol over the connector switch at any stage.

The method of emablishing a connection from a calling to a called lineallows such connection to be completed within a very short period as.the plurality of'switches used in establishing the connection areoperated at the same time.

' vertical Other features in connection with .the s stem will be pointedout in the detail descrlption to follow.

My invention is illustrated in the accompanying drawings wherein:

Figure 1 shows a subscribers line clrcuit and its controlling apparatus.at the central station. I

Fig. 2 shows a primary selector switch circuit.

.Fig. 3 shows a circuit of a connector switch and its associated trunkswitch.

Fig. 4 shows the circuit of a called subscribers line together with itscontrol apparatus.

Fig. 5 shows a key-set control circuit.

Fig. 6 shows an operators or order switch circuit.

Fig. 7 shows the. control apparatus associated with the key-board.

Fig. 8 shows an operators key-boa d and sending device.

Fig. 9 shows a control circuit for selecting an idle service trunkleading to associated connector and trunk switches.

Fig. 10 shows in detail' the wiring of the indicating lamps associatedwith the operators swltch.

Fig. 11 shows the arrangement of the various sheets.

Referring to Fig. 1,the subscribers station A is equipped with apparatususual in common battery systems. The line wires from this stationterminate at the central ofiice in a line relay 2. The line relays aredivided into groups, there being ten groups to each one hundred lines.The windings of each group of ten relays are. common to the winding of agroup relay 3 so that when any line relay is energized, the grou relayassociated with it is also energize The group relay when operated makesthe, row contact in the primary switch busy, while the line relay whenoperated makes the individual test contact in the primary switch busy IThe switch W is common to a group of one hundred lines and is made torotate whenever a call is originated. In rotating this switch picksoutan idle primary switch i nd starts the samehunting for the callingReferring now to Fig. 2, the primary switch is shown at G. On thespindle of the switch is mounted a row wiper 64 which passes over therow contacts when the switch rotates. This switch first rotates. to pickout the group of callin lines and then steps y until the cal ing line isfound. The tip and sleeve conductors are separated by the condensers 43and 44. Relay 23 and the retardation coil 26 supply talking current'tothe calling subscriber. Relay 21 is the starting relay of the primaryswitch and corresponds to the line relay 2, (Fig. 1)

as it controls the action of the operators key-set or order switch (Fig.6). Relay 22 is the row test relay while 24 is the individual testrelay. Relay 25 is operated when the key-set switch picks out the trunk.i

Relay 28 is energized whenever either the rotary or vertical magnets ofthe primary switch are operated. The circuits 'of these magnets arenormally completed through the back contacts of this relay 28, and sotherefore whenever it is actauted the magnet circuits are broken. Theaction thus set up between the relay and the magnets cause the latter tovibrate and continue to do so until their energizing circuits areopened.

Referring to Fig. 3, relays 351 and 353 are repeating relays of thetrunk switch D while relays 352 and 354 are the repeating relays of theconnector switch E. The operation of these relays control the respectivemagnets for causing the rotation and vertical stepping of the switches Dand E respectively. Relay 350 is operated when an idle switch pair isselected. Relay 357 and retardation coil 358 supply current to thecalled subscriber. Relay 355 is the ringing relay while relays 367 and368 are time element relays controlled by the disks K and L. These timeelement relays are used for causing the release of the switch D and theswitch E in case the called subscriber does not respond during apredetermined period. The two disks K and L rotate .at a certain speedin the direction indicated by the arrow.

Referring now to Fig. 4, the subscribers station and line equipment isthe same as that of Fig. 1. 7

Referring now to Fig. 5, the switch shown at Y corresponds to the switchW (Fig. 1) and picks out an idle key-set switch.

Referring now to Fig. 6, the switch M is similar and acts in the samemanner as the primary. switch C (Fig. 2). The wipers 167 connect withthe tip and sleeve side of the trunk shown in Fig. 2 over which theoperator converses with the calling subscriber. 168 is the row wiper andpicks out the particular group of trunks in which the calling trunk islocated. Relay 154 is the individual test relay and acts when the trunkin the group is found. Relay 156 is the signal relay and pulls up inseries with relay 25 (Fig; 2). Relay 152 is the starting relay andcorresponds torelay 21 (Fig. 2), while 153 is the row test relay. Relay155 is operated when the answering button 248 is depressed and connectsthe operators telephone set across the tip and sleeve conductors of thetrunk.

Referring to Figs. 7 and 8, the operators key-board, sending device andcontrolling circuits are shown. The operators keyboard shown in Fig. 8consists of five rows of buttons, each row having ten buttons. The firstfour rows of buttons R, S, T and U naeaeso I til.

are used in conjunction with the sending device for transmitting apredetermined number of impulses. Number 1 button of each of these rowsis connected to a contact on the sending device operated by the cam 232.N o. 2-button of each row is connected to the contact operated by thecam 233. The corresponding buttons in each row are connected to similarcontacts on the sending device. The contact controlled by the cam 232 isclosed just long enough to maintain relays 202 and 203 (Fig. 7)energized While one impulse is being transmitted by each of thecommutators 242 and'243. These commutators transmit impulses at the sametime. If No. 10 button is depressed relays 202 and 203 will becontrolled by the cam 241 to allow 10 impulses to be transmitted by thecommutators 242 and 243. The contacts of these commutators are connectedrespectively to normally open contacts of relays 202 and 203. When theserelays are operated the impulses are transferred to the tip and sleevesides of the service trunks in a predetermined order, depending upon theposition of the wipers 250 and 251 of the shifting switch N. v

The buttons or keys shown in the four rows R, S, T and U are of theusual locking and indicating type. When one button of a certain row isdepressed it will release the button formerly depressed. The buttons inthe row V are of thenon-locking type. When any one of these latterbuttons are depressed it will operate an associated relay. In thepresent instance I have, shown the first two buttons connected to relays200 and 201 respectively and it of course follows that there will be acorresponding relay controlled by each of the other buttons. Theoperation of these relays connects the sending device to the propergroup of service trunks. Relay 204 is the signal or control relay andoperated when an idle service trunk of the group is selected.

205 is the stepping magnetwhich controls the operation of the switch N.This stepping magnet is operated once at each rotation of the sendingdevice by means of contacts controlled by the cam 231. This switch Noperates on the back stroke of the magnet, that is to say after themagnet becomes energized and then'deenergized.

The rows of buttons It and S of Fig. 8 are used for operating theselected connector switch while the buttons T and II are used foroperating the trunkswitch. The number of the primary trunk selected bythe secondary switch is indicated to the operator'by means of two rowsof indicating lamps as shown in Fig. 10. This figure shows how the lampsare connected to the designating contacts in the bank of the secondaryswitch. Qertain of these lamps are lighted depending upon which contactsare selected by means of the wiper 190 of the switch M as shown in Fig.6. The operation of the secondary switch M in selecting the primarytrunk also causes the wiper 190 to engage corresponding designatingcontacts in the bank; In case the primary switch or trunk selectedshould be No. 21 then the designating wiper 190 would engage the firstset of contacts in the second row, causing lamps 2U and 1V to light,notifying the operator that the secondary trunk was connected to No. 21primary trunk. The operator upon receiving these signals pressescorresponding buttons in the rows T and U (Fig. 8).

Impulses from the rowsR and'll are transmitted at the same time whilethe impulses from the rows S and U are transmitted at the same time.

Fig. 9 shows the apparatus for selecting an idle connector and trunkswitch in a particular group. When a particular group is selected by theoperator the switch 0 rotates and selects an idle connector and trunkswitch in the same manner that the switch a W (Fig. 1) selects an idleprimary switch. In this particular instance, however, the selected trunkand connector switches re main in association with the operatorsposition' during two steps of the switch 0 This switch first steps toselect an idle switch pair after which the impulses are trans mitted atthe same time operating the rotary magnets of the trunk switch I) andthe connector switch E. The switch 0 is Ito then shifted and theimpulses are transmitted at the same time to operate the verticalmagnets of the trunk and connector switches. Relay 303 is a test relayfor selecting an idle switch pair while relay 305 is operated after sucha selection and'maintains' the selected switch pair busy against othercalls. Relay 305 is slow acting and will not fully restore during amomentary opening of contacts of relay 300which controls its action. 4

Relays 300 and 204 are placed in series when either of the relays areoperated by the depression of the buttons in the row V. Relay'204 willnot operate in series with the winding'of relay 300 and the resistancecoil 301, but after an idle switch pair is selected coil 301 isshuntedthereby allowing relay 204 to operate.

Each operator .is preferably provided with but a single key-board, shownin Fig.=

8, but the sending device shown in this figure may be common to aplurality of keyboards. In view of several calls being extended at thesame time each operators keyboard is provided with individualcommutators 242 and 243.

The mated switch "pairs shown in Fig. 3 are arranged in groups, thenumber of pairs in each group, of course, depend upon t'raflicconditions. Each service "trunk extending to the operators position isprovided with a selecting switch 0 which is capable of selecting an idleswitch pair in its particular group. Where several operators positionsare provided it naturally follows that the contacts of the switches 0serving particular groups of switch pairs are multipled,

The primary switches, secondary switches, trunk switches and connectorswitches are of the type shown in Patent No. 977,536 to 'This latterrelay operating closes the circuit of relay 4 which in turn connectsground to one terminal of the relay 5 and also closes the circuit of thestepping magnet 7. The stepping magnet operating closes the circuit ofrelay 6 which in turn opens the circuit of the magnet itself causing itto vibrate and step the switch W. This switch will continue to rotateuntil an idle primar switch such as shown in Fig.2 is found. s soon assuch a switch is found, the relay 5' is placed in series with relay21,(Fig. 2) by the following path: ground, contact of relay 4, 5, 18, W,14, 21, 70, contact of relay 24 to battery B. The relay 5 operatingopens the circuit of the magnet 7 bringing the switchW to rest.

Relay 21 operating closes the circuit of the rotary steppmg magnet 31 bythe following path: battery B, 80, back contact of relay 24, 71, contactof relay28, back contact of relay 22, 31 to ground. The operation ofmagnet 31 causes the switch C to rotate until.

the wiper 64 reaches the busy row contact.

The wiper 64 is carried on the same spindle with the wipers 63 and 65,and while the switch is rotating the wiper 64 passes over contactsleading to the group relay 3. As there are ten of thesegroup relays toeach one hundred lines it follows that the wiper 64 in rotating to itsextreme position will pass over ten contacts.=

There are ten sets of individual contacts arranged in vertical rowsassociated with each row contact and which the wipers 63 and 65respectively engage. It follows therefore that after the switch picksout the group inwhich a line is calling, it will afterward;

step vertically until the wipers engage the contacts ofthe calling line.9

As soon as the row contact is found, the circuit of relay 22 is closedas follows: bah tery B, 80, back contact of relay 24, 71, 22,

the key-set switch finds the trunk. Relay 64, 13, contact of-rela 3, toground. The relay 22 in operating isconnects the rotary magnet 31 and inits place connects the vertical magnet 30, thereby causing the switch tostep vertically untilthe busy individual test contact is found. As soonas such a contact is found the circuit of relay 24 is closed as follows:battery B, 24,68, contacts of relay 22, 67, '11-, contacts of relay 2 toground through the contacts of relay 1. Relay 24 operating opens thewire 71 and disconnects relay 22 which in falling backdisconnects relay24 from the wire 67 and connects it instead to wire 66, thereby placingrelays 24 and 1 in series.

The operation of relay .1 disconnects the line relay 2 and the grouprelay 3. Relay 24 connects battery to the windin of relays 23 and 25 andthe falling back 0 relay 22 connects ground to the coil 26, therebysupplying the calling subscriber with talking current.

Relay 21 remains energized until the primary switch finds the callingline and until 21, when first actuated, places battery on the wire 79,to relay 130 and also places battery to wire'62 WhlCh is connected tothe individual test contact of the key-set switch (Fig. 6).

Relay 130 closes the circuit of the stepping magnet 133 of the switch Ythrough the normally closed contacts of relays 131, 132. The magnet inoperating closes the circuit of the interrupter relay 134, therebycausing the magnet to vibrate and the switch to rotate unt1l an idlekey-set switch is found. When such a switch is found, as shown in Fig.6, relay 131 is placed in series with relay 152 by the following path:ground, contacts of relay 130, 131, 138, Y, 14.0, 152, 195, 196, 197 tobattery B through the operators jack 400. Relay 131 operating placesbattery on wire 136 to relay 132. As soon as this latter relay operates,ground is placed on the wire 138, thereby shunting relay 131. Thisdirect ground placed on wire 138 makes the wire 140 which is multipledto otherY switches busy. The operating of relay 132 also places groundon the row wiper of the key-set i switch by the following path: ground,139,

Y, 141, to the row contact.

The operation of relay 15 2 connects ground to the rotary magnet 165through the back contact of relay 153 causing the switch M to rotate.This switch will rotate until the busy row contact is found, whereuponvertical magnet 164, thereby causing the switch to step vertically untilthe busy individual test contact is found. The finding of this contactcloses the circuit of relay 154 as follows: ground, 154, 172, 62, 80,contacts of relay 21 to battery B. Relay 154 disconnects relay 152,thereby cutting off the vertical magnet and causing the keyset switch torest'on contacts leading to the calling primary trunk. Relay 152becoming disengaged opens the circuit of relay 153 and this latter relayin falling back places relays 156 and 25 in series by the followingpath: ground, back contact of relay 153, 175, back contact of relay 157,202, contact of relay 155, 156, 193, 169, 59, 25 to battery B throughthe contact of relay 24. The operating of relay 25 (Fig. 2) disconnectsrelay 21 and also relay 5 (Fig. 1). The releasing of relay 5 frees theswitch W allowing it to pick out other primary switches. Relay 156operating places battery on wires 181 and 183 causing the lamps 234 and244 to light.

As soon as relay 21 in Fig. 2 became disconnected battery was removedfrom the individual test contact of the key-set switch, thereby allowingrelay 154 to fall back. Belay 21 also releases relay 130, therebyrestoring relay 132 so as to allow the switch Yv to be used by othertrunks in picking out key-set switches.

In the present instance I have provided ten primary switches as shown inFig. 2 foreach one hundred lines. Each group of ten primary switches isin turn provided with one Y switch for picking out idle keyset switches.The percentage and grouping of the trunks and lines can be varied tosuit traflic conditions.

The wire 141 leading from the Y switch to the row contacts of thekey-set switch is not multipled., The Y switch picks out an idle key-setswitch and this places ground on the row contact ofv the selected switchand these row contacts are not multipled. This arrangement preventsinterference between other Y switches and also between the key-setswitches. Tn no case is ground placed on more than one row contact ofany key-set switchat the same time.

In Fig. 1 the switch W is individual to one hundred lines and picks outa group of primary switches, and in this case the row contacts of agroup of primary switches are multipled.

The lighting of the lamps 234 and 244 notifies the operator of a call,and she then presses button 248 closing relay 155. The operation of thisrelay connects her telephone set across the trunk wires, disconnectsrelay 156,. thereby extinguishing the lamps 234 and 244. Thedisconnecting of relay 156 also opens the circuit of relay 25,

' against other calls.

(Fig. 2) which in falling back closes the tip and sleeve conductors ofthe trunk, allowing the operator to converse with the callingsubscriber.

The operation of the switch M also causes the lighting of a lamp in eachof the rows shown in Fig. 10. The lighted lamps correspond to the numberof the primary trunk or switch which selected the calling line.

The operator after receiving the number from a calling subscriberdepresses buttons in rows R and S corresponding to the tens and unitsdigits. The operator also depresses a button in the row- T correspondingto the lamp lighted in the row TT, and also depresses a button in therow U corresponding to the lamp lighted on the row UU. After depressingthese buttons the operator depresses a button in the row V correspondingto the hundreds digits of the called subscriber. Tn the present instancewe will assume that the first button is depressed; the depressing ofthis button completes the circuit of relay 200. The operation of thisrelay connects the winding of relay 204 and the winding of' relay 300(Fig. 9) in series with the resistance coil 301. Belay 200 remainslocked to ground through the back contacts of relay 206 and the button208. Relay 300 becomes energi-zed but relay 204 is not operated due tothe high resistance of coil 301. The operation of relay 300 completesthe circuit of the stepping magnet 304 of the switch 0 by the followingpath: ground, contacts of relay 300, contacts of relay 302, winding ofmagnet 304 to battery B. The operation of the magnet. completes thecircuit of the interrupter relay 302 by the following path: ground,contacts of relay 300, 314, contacts of relay 305, 315, 316, winding ofrelay 302 to battery B. The operation of relay 302 opens the circuit ofthe magnet 304 and the magnet in restoring again allows relay 302 todrop back. This action between the magnet and relay 302 causes theswitch 0 to rotate until an idle switch pair is selected. As soon assuch a switch pair is selected, such as shown in Fig. 3, then relays 303and 350 are placed in series by the following path: battery B, contactsof relay 300, 32c, winding of relay 303, 325,312, 324, winding of relay350, 377, cam springs 370 to ground. The operation of relay 303completes the circuit of relay 305. This latter relay in operatingconnects battery directly between the winding of relay 303 and thetesting switch wiper 312, thereby rendering the contact upon which thewiper rests busy The effect of battery being connected in this mannershunts relay 303 causing it to restore, but relay 305 remains locked toground through the contacts of relay 300.

' tacts and engage the second set.

The operation of relay 305 also connects ground between the winding ofrelay 300 and the coil 301, thereby shunting out the resistance. Theshunting out of this resistance allows relay 204 (Fig. 7) to becomeenergized. The operation of this relay then causes the lamp 207 tolight, notifying the operator that an idle switch pair has beenselected. The operation of relay 204 also causes the release of theswitch M by the following path: ground, contacts of relay 204, 152,contacts of relay 160, winding of relay 157 to' battery B. The operationof this relay 157 completes the circuit of the release magnet 166 by thefollowing path: ground, contacts of relay 153, 175, contacts of relay.157 170, winding of relay 166 to battery B. The operation of this magnetcauses the restoration of the switch M thereby allowing it to be usedfor other incoming calls.

The button or key 104 is manipulated by the operator before setting upthe number on her key-board. The'operation of the button 104 allows theswitch M to be automatically restored as soon as the operators sendingdevice is placed in association with an idle switch pair. 7

In order to prevent the automatic d1sconnection the operator may neglectto press the button 104 but release the switch M by operating the button101.

In case all of the switch pairs are in use the operator can press thebutton 105 thereby connecting ground to the trunk conductor 150. Thistrunk conductor extends to the primary trunk conductor 53 through theswitch wiper 167. Connecting ground in this manner causes the operationof relay 29 which in turn connects a suitable busy tone test to thetrunk conductor 51, notifying the calling subscriber that the trunks arebusy.

The operation of relay 204 after an idle trunk switch pair is selected,also completes the circuit of the stepping magnet 205 of the switch N sothat it can be operated by the springs controlled by the cam 231 of thesending device. As soon .as the contact springs controlled by this camare operated then the magnet 205 is operated and after the contacts arebroken the switch wipers 250, 251 anti 252' leave the first set of con-It will be noted that the winding of'relay 204 is connected to batterythrough normally closed contacts of the magnet205 and to batterythroughthe contact upon which the switch wiper 252 .normally rests. After theswitch takes the first step then battery connection to the relay 204 pis controlled wholly through the contacts of the magnet 205.

After taking the first step the common wire 258 of the row of buttons Ris connected directly to the winding of relay 202 through the switchwiper 250 and the common wire of the row of buttons T is connecteddirectly to the winding of relay 203 through the wiper 251. Relays 202and 203 are maintained energized for a certain length of time, dependingupon the buttons depressed in the rows R and T. Impulses correspondingto the number of buttons depressed in these rows are transmitted bymeans of the commutators 242 and 243.

The connector switch E is operated by means of impulses from thecommutator 243 while the trunk switch D is operated by means of impulsestransmitted by the commutator 242.

After wipers of the switch N engage the second set of contacts thenrelay 202 is energized and held energized for a length of time,depending upon which button is depressed in the row R. Relay 203 islikewise held energized for length of time, depending upon which buttonis depressed in the row T, The impulses from the commutator 243 aretransmitted to the rotary relay 352 of the switch E by the followingpath: ground, commutator contacts 243, 262, contacts of relay 202,263,contacts of relay 200, 212, 311, 323, winding of relay 352 to battery B.The operation of this relay a number of times according to the buttondepressed in the row R causes a corresponding operation of the rotarymagnet362 by the following path: ground, contacts of relay 352, 374, camsprings 371, 375, winding of magnet 362 to battery B. The operation ofthis magnet causes the switch E to rotate and bring its wipers in linewith a row of contacts containing the terminals of the called line.

The impulses from commutator 242 causes the operation of the rotaryrelay 351 of the trunk switch D by the following path: ground commutatorcontacts 242, 260, contacts of relay 203, 261, contacts of relay 200,211, 310, 321, winding of relay 351 to battery B. The operation of thisrelay a number of times corresponding to the button depressed in the rowT causes the operation of the rotary magnet 361 which causes the switchD to rotate and bring its wipers in line with contacts leading to theproper group of primary trunks.

After the termination of these impulses the circuit of the magnet 205 ofthe switch N has its circuit completed by the springs controlled by thecam 231. While the magnet circuit is closed the circuit of relay 204 isbrokenv by battery being disconnected from its winding. The opening ofthis relay circuit causes its deenergization as well as thedenergization of relay 300 with which it is in series. The only effectof relay 204 restoring is to cause the signal lamp 207 to be momentarilyextinguished. Relay 300, however, in restoring removes ground from thewinding of magnet 304. thereby causing the wipers of the-switch O totake one step. In taking this step the relays 351 and 352 aredisconnected respectively from the trunk conductors 212 and 211 andrelays 353 and 354 connected instead.

As soon as the impulse transmitted by the cam 231 has been deliveredthen the stepping mafgnet 205 restores and causes the wipers 0 theswitch N to engage the th1rd set of contacts thereby connecting thecommon conductors 257 and 255 of the rows of buttons S and U to theconductors 264 and 265 respectively.

The momentary. dropping back of the relay 300 does not release relay 305as it is made slow acting for this purpose. The wiper 312 moving fromthe contact to which is directly connected the winding of relay 350still maintains that relay energized as the next contact is connected toa contact of relay 350 which engages a contact leading to the winding ofthe relay itself. With this method of control the relay 350 isoriginally energized over but a single test contact and after it'is onceenergized it is thereafter controlled over two contacts. The operationof relay 305 of course maintains direct batter connection to the twocontacts after re ay 350 is onceenergized, thereby preventing theselection of that trunk by another switch 0. The operation of relay 305also removes ground from the contact springs of magnet 304:, preventingthe operation of the interrupter relay 302.

After the switch N engages the third set of contacts then relays 202 and203 are maintained energized for length of time depending upon thebuttons depressed in the rows S and U. The operation of relay 202 causesimpulses to betr'ans'mitted from the commutator 243 to the verticalrelay 354.. The operation of this relay completes the circuit of thevertical magnet 36 1 thereby causing the. switchE to step vertically andbring its wipers to rest on contacts corresponding to the buttondepressed in the row S.

The operation of relay 203 causes impulses to be .transmitted from thecommutator 242 to the vertical. relay 353 of the switch D. The.operation of this relay completes the circuit of the vertical magnet 363and causes the switch D to step vertically and bring its wipers intoengagement.

with contacts leading to the calling primary trunk corresponding to thebutton depressed in the row U. The button in the row U of coursecorrespondsto the lamp which was lighted in the row DU.

After the impulses have been transmitted to the switches D and E thecircuit of the stepping magnet 205 of the switch N is again completed bymeans of an impulse transmitted by the cam 231. After the impulse hasbeen delivered the wipers of switch N step to their fourth or normalposition. In taking this step the wiper 252 passes over the contact 270thereby momentarily energizing relay 206. The operation of this relayremoves ground from the locking contact of relay 200 therebydisconnecting the sending device from the switches D and E. Therestoration of relay 200 severs the connection between relays 204: and300, and the latter relay in restoring removes ground from the lockingcontact of relay 305, and after a short interval of time this relayrestores and places the switch 0 in condition tobe again used for othercalls. The restoration'of this relay removes battery from the test wiper312 of the switch 0 and the restoration of relay 300 removes batteryfrom the winding of relay 303,.thereby opening the'circuit of relay 350.This relay in restoring in turn opens the circuit of the slow actingrelay 390. Before relay'390 restores ground is connected to the windingof relay 352 by the following path: ground, contacts of relay 350,contacts of relay 390, winding of relay 352 to battery B. The operationof relay 352 at this time while the switch wipers are resting oncontacts of the called line connects the test relay 366 to the testwiper 373 by the following path: ground, winding of relay 366, 382,contacts of relay 352, 381, test wiper 373. In case the called-for lineis busy rela 366 will be momentarily energized an connect grounddirectly to the conductor connected to the switch. wiper 395. As thisswitch wiper is engaging contactsof the primary trunk to which a call.-ing line is connected then relay 29 becomes operated. This relay inoperating remains locked to ground through the cam springs 38 in serieswith the resistance coil 49. This relay while operated connects asuitable. busy tone signal to the trunk conductor 51 which notifies thecalling subscriber that the called- .365 and 391 respectively of theswitches D and E thereby causing their restoration. In case thecalled-for line is not busy then relay 366 is not afiected and theconnection remains extended to the called line.

The operation of relay 352 in case the called line is not busy completesthe circuit of relay 367 by the following path: ground, contacts ofrelay 366, contacts of relay 352, 374, cam springs 371, 376, winding ofrelay 367 to battery 13, through the contact springs controlled by thedisk K. The operation of relay 367 in turn completes the circuit ofrelay 368. The operation of these two relays has no efi'ect upon theconnection unless the called subscriber fails to answer after a certaintime, that is to say after his line has been rung a certain number oftimes.

After relay 390 restores the tip and sleeve trunk conductors are closedand relay 356 has its circuit completed. by the following path: batteryB, contacts of relay 390, winding of relay 356, contacts of relay352,381, wiper 373 winding of the cut-off relay of the called line, toground. The operation of relay 356 connects ground to the Winding of theretardation coil 358 and battery to the winding of relay 357 in order tosupply talking current for the called subscriber. The operation ofrelay-356 al'socompletes the circuit of the ringing relay 355 by thefollowing path: ground, commutator I, winding of relay 355, contacts ofrelay 359, 390, contacts of relay 356 to battery B. The operation ofrelay 355 is intermittent, being controlled by the commutator I. Duringeach energization of relay 355 the trunk conductors are severed andgenerator current G is connected to the called line. When the calledsubscriber removes his receiver the tip relay 357 is energized and whenoperating completes the circuit of relay 359. The operation of thislatter relay opens the circuit of the ringing relay 355 and preventsfurther application of ringing current.

The connected switch pair is rendered busy against other calls as thestarting circuit for relay 350 is opened at the cam springs 370.

After the called subscriber replaces his receiver relay 357 restores andcompletes the circuit of the release magnets 391 and 36 5 by thefollowing path: ground, contacts of relay 357, 383, contacts of relay359, 380, to the winding of magnet 391 to battery B, and also to thewinding of the magnet 365 to battery B. The operation of these twomagnets causes the restoration of their respective switches. Therestoration of the switch E causes the cam springs 370 to operate andopen the circuit of relay 359. v

The operation of relay 357 when the called subscriber removes hisreceiver also causes ground to be removed from the locking contacts ofrelays 367 and 368 thereby causing their restoration.

The calling subscriber replacing his receiver causes the restoration ofrelay 23.. The restoration of this relay completes the circuitof therelease magnet 32 by the following path: battery B, contactsof relay 25,76, contacts of relay 21, 75, earn springs 39, 74, contacts of relay 23,73, winding of magnet 32 to ground. The operation of this magnetcauses'the restoration of the switch 0..

In case the called subscriber does not answer within a certain time, theperiod of which is controlled by the speed of the disks K and L, theswitches E and D are automatically released and a suitabled0nt answersignal connected to the calling or primary trunk. The operation ofrelays 367 and 368 have been previously described. When the cam springscontrolled by the disk K are opened relay 367 restores and a completerotation thereafter causes the restoration of relay 368. It will benoted that the cam springs controlled by the disk L are opened 'inadvance of the springs controlled by the disk K. Under these conditionsrelay 368 willbe momentarily deenergized but will become again energizedas relay 367 is operated. When the cam springs, however, controlled bythe disk K are operated relay 367 restores. At this stage no effect isproduced, but when the springs controlled by the disk L are opened relay368 becomes deenergized and as relay 367 is deenergized at this timerelay 368 remains deenergized. Under these conditions the circuit ofrelay 399 is completed by the following path: ground, contacts of relay357, 383, contacts of relay 359, contacts of relay 367, 385, contacts ofrelay 368, 386; contacts of relay 356, 387, winding of relay 399 tobattery B. The operation of relay 399 connects ground to the wiper 395thereby operating relay 27 associated with the primary trunk. Theoperation of this latter relay connects a suitable -dont answer signalto the trunk conductor 51 notifying the calling subscriber that thecalled subscriber does not respond. The operation of relay 399 alsocompletes the circuit of relay 359. The operation of this relay whilerelay 357 is denergized allows the circuits of the release magnets 365and 391 to be completed by the path previously traced.

The calling subscriber receiving the indication that the subscribercalled for does not respond replaces his receiver and causes therestoration of the switch C as previously described. The restoration ofthis switch opens the locking relay 27 thereby removing the dont answersignal from the trunk conductor 51.

From the foregoing description it will be seen that the connectionsbetween the calling and called subscribers lines are effected with greatrapidity. The directively driven switches for effecting the connectionsare operated at the same time as the operators eiuipment is so arrangedthat two groups 0 impulses are transmitted at the same time to operatethese switches. 'So far as I am aware this is a new method ofestablishing connections as it is the usual custom in automatic orsemi-automatic systems to operate the directively driven switches one ata time in a'certain order.

It will also be noted that the trunk switches are not provided withtesting contacts but are driven directly to the primary trunks to whichthe calling lines are connected. The service trunks which may be few innumber are provided with the necessary testing contacts for selecting anidle switch pair.

In the present instance I have shown the service trunks terminating incontacts of relays associated with the operators positions. Of course,these trunks can terminate on what may be termed trunk jacks. Thesetrunk jacks can be multipled to different operators positions, asuitable busy tone signal being providedeither in the form ofbusy'indicatinglamps or the ordinary audible test such as commonly usedin connection with multiple switch boards.

Instead of providing relays or trunk jacks the row of buttons designatedas V can be provided with the proper number of contacts so that when aparticular button is depressed it will connect the controlling apparatusshown in Fig. 7 to the proper service trunk. This row of buttons can beprovided with a release magnet for releasing the'depressed button uponthe operation of relay 206 which can be provided with a suitable contactfor that purpose.

Instead of providing the designating lamps shown in Fig. 10 and whichare connected to contacts inthe bank of the operators switch these lampscan be dispensed with. In place of the lamps the proper contacts in thebank can be connected to corresponding contacts controlled by the camson the sending device, Fig. 8. In this event the rows of buttons T and Uwill not be used as the common wires 255and 256 would be connectedrespectively to the tip and sleeve conductors of the wiper 190 of Fig.,6, and the ground connection omitted. With this arrangement button 104will not be operated and the switch M would remain in engagement withthe primary trunk until connection was eifected with the calledline. Thedesignating contacts in the bank such as shown in Fig. 10 instead ofbeing'connected to the lamps will be connected to the sending device inthe sa'memanner as the contacts in the rows T and U of the key board.

From the foregoing it will be seen that many modifications may be madewith the type system disclosed without departingfrom the spirit of myinvention.

Having thus described my invention, what I desire to secure by LettersPatent is:

1. A telephone exchange system including a calling subscribers line,terminals therefor at the exchange, of a primary trunk circuit adaptedto, be automatically connected with said line upon the initiation of acall, an operators position and. order trunk leading thereto, anelectrically controlled selective switch at the exchange, means forinitiating travel thereof to connect said primary trunk and order trunkin response to the operation of said selective switch, it calledsubscribersw line, terminals therefor at the exchange operators meansfor transmitting directive currents over a circuit separate from saidtrunk line to establish a connection from the terminals of the callingline to terminals of the called line, with means for freeing said ordertrunk at the initial transmission of the directive currents.

2. A telephone'exchange system including a calling subscribers line,terminals therefor at an exchange, a central office primary trunkcircuit adapted to be automatically connected with the line upon theinitiation of a call, an operators position,'an order trunk leadingthereto, an electrically controlled selector switch at the exchange,means for initiating travel thereof to connect said primary trunkcircuit and order trunk in response to the operation of said selectiveswitch, a called subscribers line, terminals therefor at the exchange, apair of directively operable selective switches, one of said switchescontaining in its contact banks terminals of the primary trunk and theother terminals of the called line, operators means for electricallycontrolling the adjustment of said selective switches to complete theconnection from the terminals of the primary trunk to the terminals ofthe called line.

3. In a telephone exchange system, a number of subscribers lines, anumber of primary trunks less than the number of lines, each trunkterminating at one end in a primary selector switch and at the other.end in terminals associated with a trunk switch, an operators position,a secondary switch associated with said position and containingterminals of" a number of said primary trunks, all of said secondaryswitches adapted to be started up to test and connect with terminals ofsaid primary trunks, additional means controlled at said operatorsposition for causing the trunk switch to efi'ect connection withterminals of the primary trunk.

4 A telephone exchange system including telephone lines, primaryselectors for automatically connecting calling lines with primarytrunks, of a plurality of permanently connected switch pairs at theexchange, each pair including a connector switch provided with contactsfor selecting the called line, the other switch of each pair beingatrunk switch for connecting with the primary

